In moving from track to track, a disk drive actuator uses a seek technique that involves accelerating the actuator assembly and decelerating the actuator assembly to a stop at the target track. Various seek modes are satisfactorily used, but the most difficult problem has been bringing the head to a smooth stop over the desired track in the shortest possible time. The settle mode, which is the transition between the seek operation and the track follow mode, during which the head motion is stabilized to permit the start of read or write operations has been the most difficult portion of the high speed access disk drive design.
In addition to seek modes that involve multiple track seeks, involving seek and settle modes prior to track follow operation, the single track seek offers a unique opportunity for performance enhancement. The most common seek is to the same track or cylinder. The single track seek is the most frequently occurring movement of the actuator between tracks in a properly organized data storage system. Thus the seeks to the same track or an adjoining track are combined, most seeks by the device actuator are included. Accordingly, device performance can be enhanced if a single track seek can be accomplished by a simplified, shortened procedure. The optimum simplicity and performance can normally be achieved if the single track seek can utilize an error signal that causes a single track displacement without entering the seek mode.